In recent years, as mobile communication terminals such as cellular phones have become more sophisticated, the speed of wireless communication has increased. Since a communication speed is proportional to the bandwidth of a frequency to be used, a frequency band required for communication has increased and accordingly the number of installed high frequency filters required for mobile communication terminals has also increased. Furthermore, research on the field of spintronics which is expected to be applied to new high frequency components has been actively conducted. One of the phenomena attracting attention in this field is a spin torque resonance phenomenon by a magnetoresistance effect element (refer to Nature, Vol. 438, no. 7066, pp. 339 to 342, 17 Nov. 2005).
For example, when an alternating current (AC) current is caused to flow to a magnetoresistance effect element and at the same time that a static magnetic field is applied using a magnetic-field applying mechanism, ferromagnetic resonance can be caused in the magnetization of a magnetization free layer included in the magnetoresistance effect element and a resistance value of a magnetoresistance effect element oscillates periodically at a frequency corresponding to a ferromagnetic resonance frequency. Furthermore, the resistance value of the magnetoresistance effect element also oscillates when a high frequency magnetic field is applied to the magnetization free layer in the magnetoresistance effect element. A ferromagnetic resonance frequency changes in accordance with the intensity of the static magnetic field applied to the magnetoresistance effect element and this resonance frequency is generally included in a high frequency band of several to several tens of GHz.
Japanese Unexamined Patent Application, First Publication No. 2017-63397 describes a technique for changing a ferromagnetic resonance frequency by changing the intensity of a magnetic field applied to a magnetoresistance effect element and proposes a device such as a high frequency filter using this technique.
Examples of a magnetic-field applying mechanism configured to apply a magnetic field to a magnetoresistance effect element include an electromagnet type and a strip line type in Japanese Unexamined Patent Application, First Publication No. 2017-63397, but a detailed constitution thereof is not described. As a method of applying a magnetic field to a magnetoresistance effect element, generally, a method of applying a magnetic field generated from a magnetic member such as a yoke to a magnetoresistance effect element is conceivable. However, the inventor's research has found in this method that there is a concern of deterioration of a high frequency characteristic of a device due to a capacitance component present between a yoke and a high frequency signal line.